A press pack semiconductor device allows improvements in power density due to heat release/dissipation from two surfaces and provides high reliability under high voltage and large current operating conditions. The press pack semiconductor device has a structure in which a plurality of semiconductor elements are provided inside an insulating frame and then sandwiched between upper and lower electrode blocks such that the inside of the insulating frame is sealed. Internal electric contact is maintained by a force applied to the upper and lower electrode blocks from the outside.
However, when one or more of the internal semiconductor elements of the press pack semiconductor device fails or is otherwise damaged, the press pack semiconductor device may be short-circuited even though other internal elements remain functional, and the overall press pack device may become inoperable. Therefore, in using press pack semiconductor devices these press pack devices are often connected in series with each other such that if one is short-circuited the larger system will not immediately fail.
However, when an excessive load is applied to the faulty and damaged semiconductor element and an overcurrent flows, there is a case where the semiconductor element is melted due to a remarkable increase in temperature due to the high voltages and large currents being passed through elements. As the semiconductor element is melted or even vaporized, there is a concern that internal pressure will increase and the semiconductor device may explode and damage other components or devices. When the semiconductor device explodes, pieces of the device may be scattered around, and critical circuits or a cooling device on the periphery of the semiconductor device may be damaged. Thus, the larger system becomes inoperable as well.